add ability to specify source as a URL scheme

README.md

@@ -64,7 +64,11 @@ Analyze and image and get a pass/fail result based on the image efficiency and w
 **With Multiple Image Sources and Container Engines Supported**
 With the `--source` option, you can select where to fetch the container image from:
 ```bash
-dive <your-image-tag> --source podman
+dive <your-image> --source <source>
+```
+or
+```bash
+dive <source>://<your-image>
 ```
 
 With valid `source` options as such:

cmd/analyze.go

@@ -39,16 +39,26 @@ func doAnalyzeCmd(cmd *cobra.Command, args []string) {
 		os.Exit(1)
 	}
 
-	engine, err := cmd.PersistentFlags().GetString("source")
+	var sourceType dive.ImageSource
-	if err != nil {
+	var imageStr string
-		fmt.Printf("unable to determine engine: %v\n", err)
+
-		os.Exit(1)
+	sourceType, imageStr = dive.DeriveImageSource(userImage)
+
+	if sourceType == dive.SourceUnknown {
+		sourceStr, err := cmd.PersistentFlags().GetString("source")
+		if err != nil {
+			fmt.Printf("unable to determine image source: %v\n", err)
+			os.Exit(1)
+		}
+
+		sourceType = dive.ParseImageSource(sourceStr)
+		imageStr = userImage
 	}
 
 	runtime.Run(runtime.Options{
 		Ci:         isCi,
-		Source:     dive.ParseImageSource(engine),
+		Source:     sourceType,
-		Image:      userImage,
+		Image:      imageStr,
 		ExportFile: exportFile,
 		CiConfig:   ciConfig,
 	})

dive/get_image_resolver.go

@@ -5,6 +5,8 @@ import (
 	"github.com/wagoodman/dive/dive/image"
 	"github.com/wagoodman/dive/dive/image/docker"
 	"github.com/wagoodman/dive/dive/image/podman"
+	"net/url"
+	"strings"
 )
 
 const (
@@ -24,11 +26,11 @@ func (r ImageSource) String() string {
 
 func ParseImageSource(r string) ImageSource {
 	switch r {
-	case "docker":
+	case SourceDockerEngine.String():
 		return SourceDockerEngine
-	case "podman":
+	case SourcePodmanEngine.String():
 		return SourcePodmanEngine
-	case "docker-archive":
+	case SourceDockerArchive.String():
 		return SourceDockerArchive
 	case "docker-tar":
 		return SourceDockerArchive
@@ -37,6 +39,28 @@ func ParseImageSource(r string) ImageSource {
 	}
 }
 
+func DeriveImageSource(image string) (ImageSource, string) {
+	u, err := url.Parse(image)
+	if err != nil {
+		return SourceUnknown, ""
+	}
+
+	imageSource := strings.TrimPrefix(image, u.Scheme+"://")
+
+	switch u.Scheme {
+	case SourceDockerEngine.String():
+		return SourceDockerEngine, imageSource
+	case SourcePodmanEngine.String():
+		return SourcePodmanEngine, imageSource
+	case SourceDockerArchive.String():
+		return SourceDockerArchive, imageSource
+	case "docker-tar":
+		return SourceDockerArchive, imageSource
+
+	}
+	return SourceUnknown, ""
+}
+
 func GetImageResolver(r ImageSource) (image.Resolver, error) {
 	switch r {
 	case SourceDockerEngine: